Smelly water and dead fish at Palma Sola Park. The cause is natural, county says

Dead fish and discolored, smelly water are affecting two connected ponds at Palma Sola Park in Bradenton.

The water began to change over the weekend, residents told Manatee County staff. Some suspected a sanitary sewer overflow from one of the nearby neighborhoods.

After investigating the area and taking water samples on Monday, however, county staff say that a natural phenomenon is behind the fish kill.

Scott Browning, the county’s senior environmental specialist, said that recent cold weather caused a rapid change in water conditions.

“Sometimes when you get a cold snap like we just did, the water in ponds can flip,” Browning said.

Browning explained that cold water at the surface of a pond pushes into the deeper portions and brings up water with low dissolved oxygen levels, which can result in a fish kill. It also brings up sediment that can release sewer-like hydrogen sulfide odors.

Darshan Dorsey, a visitor to the park on Monday, experienced the stench first hand.

“As you move more towards the still water, it’s quite potent,” Dorsey said. “As far as recreational value goes, that’s not good. It’s definitely something for the scientists and our loyal public servants to take a look at.”

Browning said the ponds have experienced a similar episode in the past, and it is a natural phenomenon that will run its course.

At one point on Monday, dozens of dead fish were visible floating on the surface and at the edges of one of the ponds.

By around 3 p.m., the stench remained, but fewer dead fish were present thanks to a group of vultures that descended on the park.

“The fact that there’s not other wildlife dying is a very good sign,” Browning said. “And it’s a good sign that the vultures are eating the fish. Nature has a way of taking care of these things.”

Browning is with the Manatee County Environmental Protection Division, which investigates complaints about issues including surface water quality, fish kills and algae blooms.

Manatee County Utilities Department staff also conducted water sampling to determine if a sanitary sewer overflow was affecting the ponds.

There was no evidence of a spill occurring, according to utilities spokeswoman Amy Pilson.

Browning said that temperature-related changes are fairly common in small ponds. A Lakewood Ranch neighborhood experienced a similar issue several weeks ago.

“We recommend they put in some kind of aeration device to stir the water up, keep it more mixed and prevent that,” Browning said.

This story was originally published November 19, 2019 at 8:01 AM.